Metal plating of substrates

ABSTRACT

Substrates are plated with metals by subjecting the substrate to low oxidation state phosphorus compounds, usually in a solvent, followed by subjecting the treated substrate to a metal salt or complex thereof. The low oxidation state phosphorus compounds, wherein the phosphorus has an oxidation state of less than 5, i.e., an oxidation number of -3 to +3, can be prepared by reacting elemental phosphorus, preferably elemental white phosphorus (which include various impure or commercial grades sometimes referred to as yellow phosphorus), with a nucleophilic reagent or organometallic compound. The resulting treated substrate is electroless metal plated and/or electroplated to provide an adherently bound metal layer on the substrate. In one embodiment, the substrate is subjected to a low oxidation state phosphorus compound and thereafter electroless metal plated.

United States Patent Lin [54] METAL PLATING OF SUBSTRATES [72] Inventor:Kingso Chingtsung Lin, Niagara Falls,

[73] Assignee: Hooker Chemical Corporation, Niagara Falls, N.Y.

[22] Filed: July3, 1969 21 Appl. No.: 839,080

Related us. Application Data [63] Continuation-impart of Ser. No.750,477, Aug. 6,

I968, abandoned.

Bayard, J. J., Electrodeposition on Plastic Materials in Metal Industry,May 1940, p. 256

[451 Mar. 21, 1972 Primary ExaminerAlfred L. Leavitt AssistantExaminer-Janyce A. Bell AttorneyPeter F. Casella, Donald C. Studley,Richard P. Mueller, James F. Mudd and Edward A. Meilman [5 7] ABSTRACTSubstrates are plated with metals by subjecting the substrate to lowoxidation state phosphorus compounds, usually in a solvent, followed bysubjecting the treated substrate to a metal salt or complex thereof. Thelow oxidation state phosphorus compounds, wherein the phosphorus has anoxidation state of less than 5, i.e., an oxidation number of -3 to +3,can be prepared by reacting elemental phosphorus, preferably elementalwhite phosphorus (which include various impure or commercial gradessometimes referred to as yellow phosphorus), with a nucleophilic reagentor organometallic compound. The resulting treated substrate iselectroless metal plated and/or electroplated to provide an adherentlybound metal layer on the substrate. In one embodiment, the substrate issubjected to a low oxidation state phosphorus compound and thereafterelectroless metal plated.

50 Claims, No Drawings METAL PLATING F SUBSTRATES This is acontinuation-in-part of application Ser. No. 750,477, filed Aug. 6, 1968and now abandoned.

BACKGROUND OF THE INVENTION There is a rapidly increasing demand formetal plated articles, for example, in the production of low costplastic articles that have a simulated metal appearance. Such articlesare in demand in such industries as automotive, home appliance, radioand television and for use in decorative containers and the like.Heretofore, the metal plating of plastics and the like has required manyprocess steps, and generally such processes have been applicable to onlyone or a few related substrates.

It is an object of this invention to provide a simple process for themetal plating of substrates. Another object of the invention is toprovide a process that is applicable to the plating of many differentsubstrates particularly the thermoplastic polymers. A further object ofthe invention is to provide articles having an adherent metal coatingthat is resistant to peeling, temperature cycling, and corrosion. Suchcoatings are electrically conductive whereby static charges are readilydissipated from the surfaces. The metal coatings further serve toprotect the articles from abrasion, scratching and marring, reduce theirporosity and improve their thermal conductivity. The process of thisinvention can be used for unidirectional mirrors and the like; water andliquid collecting devices and the like; protective coatings on houses,cars, boats, power line poles, street lights and the like; in thermalcontrol of clothing, houses and the like; and the like.

SUMMARY OF THE INVENTION This invention provides a process whichcomprises forming a metal-phosphorus coating at the surface of asubstrate to render the surface susceptible to conventional electrolessplating and/or electrolytic plating.

More particularly, this invention provides a process which comprisessubjecting a substrate to a low oxidation state phosphorus compound soas to deposit the low oxidationstate phosphorus compound at the surfaceof the substrate and thereafter subjecting the thus-treated substrate'toa solution of a metal salt or complex thereof to form a metal-phosphoruscoating. In one aspect of the invention, the resultant substrate iselectroplated to deposit an adherent metal coating on the substrate. Inanother aspect of the invention, the treated substrate is subjected toelectroless metal plating to deposit an electroless conductive coatingonthe surface. Thereafter, the article is electroplated so as to depositan adherent metal coating of the desired thickness on the electrolessconductive coating.

Further, in accordance with the invention, there is provided a processwhich comprises subjecting a substrate to a low oxidation statephosphorus compound andthereafter subjecting the substrate toelectroless metal plating to deposit an electroless conductive coatingon the substrate. Thereafter, the article is electroplated so as todeposit an adherent metal coating of desired thickness on theelectroless conductive coating.

Also in accordance with the invention, there is provided an articlehaving a metal-phosphorus coating adherently formed at the surface ofthe substrate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The process of this inventionis applicable to substrates, such as plastics and to other substantiallynonmetallic substrates. Suitable substrates include, but-are not limitedto, cellulosic and ceramic materials such as cloth, paper, wood, cork,cardboard, clay, porcelain, leather, porous glass, asbestos cement, andthe like.

Typical plastics to which the process of this invention is applicableinclude the homopolymers and copolymers of ethylenically unsaturatedaliphatic, alicyclic and aromatic hydrocarbons such as polyethylene,polypropylene, polybutene', ethylenepropylene copolymers; copolymersofethylene or propylene with other olefins, polybutadiene; polymers ofbutadiene, polyisoprene, both natural and synthetic, polystyrene andpolmers of pentene, hexene, heptene, octene, 2-methylpropene,4-n1ethyl-hexene-I, bicyclo-(2.2.l )-2-heptene, pentadiene, hexadiene,2,3-dimethylbutadiene-1,3,4- vinylcyclohexene, cyclopentadiene,methylstyrene, and the like. Other polymers useful in the inventioninclude polyindene, indenecoumarone resins; polymers of perhaloethylenessuch as poly(tetrafluoroethylene) and poly(monochlorotrifluoroethylene);polymers of acrylate esters and polymers of methacrylate esters,acrylate and methacrylate resins such as ethyl acrylate, n-butylmethacrylate, isobutyl methacrylate, ethyl methacrylate and methylmethacrylate; alkyd resins; cellulose derivatives such as celluloseacetate, cellulose acetate butyrate, cellulose nitrate, ethyl cellulose,hydroxyethyl cellulose, methyl cellulose and sodium carboxymethylcellulose; epoxy resins; furan resins (furfuryl alcohol orfurfural-ketone); hydrocarbon resins from petroleum; isobutylene resins(polyiso-butylene); isocyanate resins (polyurethanes); melamine resinssuch as melamineformaldehyde and melamine-urea-formaldehyde;oleo-resins; phenolic resins such as phenol-formaldehyde,phenolicelastomer, phenolic-epoxy, phenolic-polyamide, andphenolic-vinyl acetals; polyamide polymers, such as polyamides,polyamide-epoxy and particularly long chain synthetic polymeric amidescontaining recurring carbonamide groups as an integral part of the mainpolymer chain; polyester resins such as unsaturated polyesters ofdibasic acids and dihydroxy compounds, and polyester elastomer andresorcinol resins such as resorcinol-formaldehyde, resorcinol-furfural,resorcinol-phenol-formaldehyde, resorcinol-polyamide andresorcinol-urea; rubbers such as natural rubber, synthetic polyisoprene,reclaimed rubber, chlorinated rubber, polybu' tadiene, cyclized rubber,butadiene-acrylonitrile rubber, butadiene-styrene rubber, and butylrubber; neoprene rubber (polychloroprene); polysulfides (Thiokol);terpene resins; urea resins; vinyl resins such as polymers of vinylacetal, vinyl acetate or vinyl alcohol-acetate copolymer, vinyl alcohol,vinyl chloride, vinyl butyral, vinyl chloride-acetate copolymer, vinylpyrrolidone and vinylidene chloride copolymer, polyformaldehyde;polyphenylene oxide; polymers of diallyl phthalates and phthalates;polycarbonates of phosgene or thiophosgene and dihydroxy compounds suchas bisphenols, thermoplastic polymers of bisphenols and epichlorohydrin(tradenamed Phenoxy polymers); graft copolymers and polymers ofunsaturated hydrocarbons and an unsaturated monomer, such as graftcopolymers of polybutadiene, styrene and acrylonitrile, commonly calledABS resins; ABS-polyvinyl chloride polymers, recently introduced underthe trade name of Cycovin; and acrylic polyvinyl chloride polymers,known by the trade name of Kydex 100.

The polymers of the invention can be used in the unfilled condition, orwith fillers such as glass fiber, glass powder, glass beads, asbestos,talc and other mineral fillers, wood flour and other vegetable fillers,carbon in its various forms, dyes, pigments, waxes and the like. If awax is used as a filler, it has been found that the harder the wax, themore adherent the metal will be bound to the substrate.

The substrates of the invention can be in various physical forms, suchas shaped articles, for example, moldings, sheets, rods, and the like;fibers, films and fabrics, and the like.

In the process of the invention, the substrate is subjected to atleastone low oxidation state phosphorus compound, usually in a solvent. Thelow oxidation state phosphorus compound, wherein the has an oxidationstate of less than 5, i.e., an oxidation number of 3 to +3, can beprepared by reacting elemental phosphorus, preferably elemental whitephosphorus (which includes various impure or commercial grades sometimesreferred to as yellow phosphorus), with a suitable nucleophilic reagentor organometallic compound (including Grignard reagents). Suitablenucleophilic reagents include basic compounds having an unshared pair ofelectrons on a carbon, oxygen, nitrogen, sulfur, or phosphorus atom. Thepreferred nucleophilic reagents have the formula M2,,

wherein M is an alkali metal (Group 1A) or an alkaline earth metal(Group 11A), y is l or 2, and Z is hydroxide, alkoxide, amide, sulfite,thiosulfate, mercaptide, cyanate, thiocyanate, cyanide, azide and thelike.

The organometallic compounds have the general formula R,.D wherein D isa metal selected from Groups 1A, 11 and l 1 1A ofthe Periodic Table, xis l to 3, and R is alkyl of one to 18 carbon atoms, aryl of six to 18carbon atoms, alicyclic of five to 18 carbon atoms, aralkyl of six to 18carbon atoms and alkylaryl of six to 18 carbon atoms. The R groups canbe unsubstituted or substituted with halogen, nitro groups and the like.Typical organometallic compounds include di(n-butyl) cadmium,diphenylcadmium, dimethylcadmium, diisopropylcadmium, di(p-nitrophenyl)cadmium, triphenylmethylsodium, dianilinocadmium, diethylzinc,di(o-tolyl) zinc, methylzinc chloride, phenyllithium, butyllithium,cyclohexyllithium, triethylaluminum and the like.

The organometallic compounds include Grignard reagents which are thewell-known alkylmagnesium halides such as methylmagnesium iodide,ethylmagnesium bromide, n-propylmagnesium chloride, isopropylmagnesiumchloride, phenylmagnesium bromide and the like.

Useful hydroxides include sodium hydroxide, potassium hydroxide, lithiumhydroxide, cesium hydroxide, magnesium hydroxide, strontium hydroxide,calcium hydroxide, barium hydroxide and the like.

The metal alkoxides are alcohols or phenols in which the hydrogen atomof the hydroxyl group has been replaced by the metal. Thus, the termalkoxide encompasses alkylates and phenates. In these compounds, Z isOR, which represents the alcohol or phenol without the hydroxylic orphenolic hydrogen and where R is as hereinbefore defined. The alcohol orphenol from which the alkoxide is derived can be unsubstituted orsubstituted with hydrocarbon groups, halogen, nitro groups and the like.Typical alkoxides are lithium methoxide, lithium ethoxide, sodiummethoxide, sodium ethoxide, sodium propoxide, potassium methoxide,potassium ethoxide, cesium ethoxide, barium methoxide, calcium ethoxide,sodium pentadecanoxide, sodium phenate, potassium phenate, calciumphenate, sodium chlorophenate, potassium chlorophenate, bariumchlorophenate, sodium phenylethoxide, potassium phenylethoxide,magnesium phenylethoxide, sodium p-nitrophenoxide, calciump-nitrophenoxide, sodium ,B-naphthoxide, potassium B-naphthoxide, barium,8- naphthoxide and the like.

The metal amides are compounds where Z is RR"N- wherein R and R" areindividually selected from the group consisting ofhydrogen, R and The Rgroups can be unsubstituted or can be substituted with halogen, nitrogroups, hydrocarbon groups and the like. Useful metal amides includesodium amide, potassium amide, lithium amide, cesium amide, magnesiumamide, calcium amide, barium amide, sodium anilide, potassiumnitroanilide, calcium chloroanilide, sodium ethyl amide, potassiumdiethyl amide, sodium propyl amide, sodium cyclopentyl-amide, N- sodiumacetamide and the like.

Useful sulfites and thiosulfates include sodium sulfite, potassiumsulfrte, lithium sulfite, calcium sulfite, barium sulfite, magnesiumsulfite, sodium thiosulfate, potassium thiosulfate, calcium thiosulfate,barium thiosulfate, mangesium thiosulfate and the like.

The mercaptides are metallic derivatives of mercaptans in which thesulfur hydrogen is replaced by a metal. Typical examples which includesodium methylmercaptide, potassium ethylmercaptide, cesiumpropylmercaptide, calcium butylmercaptide, barium octylmercaptide,sodium phenylmercaptide, potassium nitrophenylmercaptide, calciumchlorophenylmercaptide, sodium tolylmercaptide, potassiumpethylphenylmercaptide and the like.

Useful cyanate, thiocyanate, cyanide and azide compounds include sodiumcyanate, potassium cyanate, barium cyanate, calcium cyanate, sodiumthiocyanate, potassium thiocyanate, lithium thiocyanate, magnesiumthiocyanide, barium thiocyanate, sodium cyanide, potassium cyanide,strontium cyanide, sodium azide, potassium azide, barium azide and thelike.

The phosphorus is reacted with the nucleophilic reagent ororganometallic compound in a mole ratio that can vary from /1 to H100phosphorus to reagent or compound, preferably from lO/l to l/lO. Thereaction is generally conducted below the decomposition point of thenucleophilic reagent or organometallic compound and below the boilingpoint of the solvent, ifa solvent is used, preferably from about 20 C.to about 200 C. and more preferably at about 0 C. to about 60 C. Thereaction time varies depending on the nature of the nucleophilic reagentor organometallic compound, the solvent and the temperature but isgenerally in the range of about 1 minute to 24 hours.

The resulting low oxidation state phosphorus compounds are usuallyemployed in a solvent. The phosphorus can be reacted with a nucleophilicreagent or organometallic compound in the solvent or the phosphorus canbe reacted with the reagent or compound and thereafter combined with thesolvent. For example, phosphorus can be reacted with sodium ethoxide inthe presence of ethanol or the phosphorus can be reacted with sodiumethoxide and combined with ethanol. In a similar manner, the phosphoruscan be reacted with a mixture of nucleophilic reagents in a commonsolvent or reacted with each reagent and the products combined. Suitablesolvents or diluents for the low oxidation state phosphorus compoundsare solvents or mixtures thereof that dissolve the phosphorus compoundsand do not interact with the compounds to rapidly destroy theiractivity. Solvents that reduce or only slowly destroy the activity ofthe phosphorus compounds of this in vention can be used if they havecompensating properties, such as the property ofswelling the surface ofthe substrate.

Suitable solvents are generally neutral or only weakly acidic. They canbe polar or non-polar. Strongly solvating solvents, either protic ordi-polar aprotic are preferred. Solvents that swell a plastic surface orpenetrate below the surface without detrimentally affecting the surfaceare preferable. Typical solvents or diluents can be aliphatic oraromatic and usually contain up to 30 carbon atoms. They includealiphatic and aromatic hydrocarbons, ethers, and thioethers; carbonylcompounds such as esters and ketones; nitrogen-containing compounds suchas amides, amines, nitriles and nitro compounds; alcohols; phenols;mercaptans; and halogen-containing compounds. Examples of solventsinclude alcohols such as methanol, ethanol, propanol, butanol, octylalcohol, decyl alcohol, benzyl alcohol, cyclohexanol, ethylene glycol,glycerol, and the like; aromatic hydrocarbons of six to 18 carbon atomssuch as benzene, toluene, xylene, ethyl benzene, naphthalene, tetralin,and the like; ethers such as methyl ether, ethyl ether, propyl ether,isopropyl ether, methyl t-butyl ether, 3-methoxyhexane, anisol,carbitol, diphenyl oxide, and the like; alkanes of one to 18 carbonatoms such as methane, ethane, propane, hexane, octane, decane,octadecane, cyclopentane, cyclooctatetraene, and the like; dipropylsulfide; dibutyl sulfide; dimethyl sulfoxide; tetrahydrothiophene; butylformate; methyl acetate; ethyl acetate, benzyl acetate; phenylcarbonate; formamide; dimethylformamide; acetamide; Nmethyl-2-pyrrolidone; acetone; nitrobenzene; monochlorobenzene;acetophenone; isophorone;

tetrahydrofuran; halogenated hydrocarbons and halocarbons such aschloroform, carbontetrachloride, trichloroethylene, trichloroethane,dichloropropane, ethyl dibromide, ethylchlorobromide, and the like;aniline; hexylamine; acetonitrile; benzonitrile;hexamethylphosphoramide; dodecylmercaptan; phenols such as phenol,resorcinol, catechol, hydroquinone, para-tertiary-butyl phenol,parachlorophenol, para-phenyl phenol, cresol, thiophenol, mercaptophenoland the like; and the like solvents or diluents.

The amount of low oxidation state phosphorus compounds in solution, asmeasured by the amount of phosphorus therein, can vary from about 0.0001weight percent phosphorus based on the total weight of the solution toabout a saturated solution, preferably from 0.01 to 0.5 percentphosphorus.

As a result of the treatment with the low oxidation state phosphoruscompound, the compound is deposited at the surface of the substrate. Bythis is meant that the low oxidation state phosphorus compound can belocated on the surface, embedded in the surface and embedded beneath thesurface of the substrate. The location of the low oxidation statephosphorus compound is somewhat dependent on the action of the solventon the substrate.

Prior to contacting the substrate with the low oxidation statephosphorus compounds, the surface of the substrate should be clean.However, it is not necessary to subject the surface to special treatmentsuch as etching, polishing and the like. The subjection of the substrateto the solution of low oxidation state phosphorus compounds is generallyconducted at a temperature below the softening point of the substrate,and below the softening point of the solvent. Generally, the temperatureis in the range of about 30 to 135 C., but preferably in the range ofabout to 100 C. The contact time varies depending on the nature of thesubstrate, the solvent and the temperature, but it is generally in therange of about 1 second to 1 hour or more, preferably in the range of 1to 10 minutes.

Following the first treatment step, the substrate can be rinsed with asolvent, and then dried by merely exposing the substrate to theatmosphere or to inert atmosphere such as nitrogen, carbon dioxide, andthe like, or by drying the surface with radiant heaters or in aconventional oven. Drying times can vary considerably, for example, from1 second to 30 minutes or more, preferably 5 seconds to 10 minutes, morepreferably 5 to 120 seconds. The rinsing and drying steps are optional.The treated substrate is thereafter stored before further treatment orcan be immediately subjected to the subsequent processing steps.

In the second treatment step of the process of the invention, thephosphorus-treated substrate is contacted with a solution of a metalsalt or a complex of a metal salt, which is capable of reacting with thelow oxidation state phosphorus compound to form a metal-phosphoruscoating. The term metal-phosphorus coating, as used herein, means thecoating which is formed at the surface of the substrate. Without beinglimited to theory, the metal-phosphorus coating may be an ionic compoundor a solution (alloy). The metals generally employed are those of Groups1B, IIB, IVB, VB, VIB, VIIB and VIII of the Periodic Table appearing atpages 6061 of Langes Handbook of Chemistry (Revised tenth Ed.). Thepreferred metals are copper, silver, gold, chromium, manganese, cobalt,nickel, palladium, titanium, zirconium, vanadium, tantalum, cadmium,tungsten, molybdenum, and the like.

The metal salts that are used in the invention can contain a widevariety of anions. Suitable anions include the anions of mineral acidssuch as sulfat'e, chloride, bromide, iodide, fluoride, nitrate,phosphate, chlorate, perchlorate, borate, carbonate, cyanide, and thelike. Also useful are the anions of organic acids such as formate,acetate, citrate, butyrate, valerate, caproate, heptylate, caprylate,naphthenate, 2-ethyl caproate, cinnamate, stearate, oleate, palmitate,dimethylglyoxime, and the like. Generally the anions of organic acidscontain one to 18 carbon atoms.

Some useful metal salts include copper sulfate, copper chloride, silvernitrate and nickel cyanide.

The metal salts can be complexed with a complexing agent that produces asolution having a basic pH 7). Particularly useful are the ammoniacalcomplexes of the metal salts, in which one to six ammonia molecules arecomplexed with the foregoing metal salts. Typical examples include NiSO-6NH NiCl 'NH Ni(C H OO) -6NH CuSO.,-6NH CuCl -6NH AgNO '6NH NiSO,-3NHCuSO -4NH Ni(NO '4Nl-l and the like. Other useful complexing agentsinclude quinoline, amines and pyridine. Useful complexes includecompounds of the formula MX Q wherein M is the metal ion, X is chlorineor bromine and Q is quinoline. Typical examples include: CoCl- Q CoBr QNiCl Q NiBr Q Nil Q MnCl Q CuCl Q CuBr Q 2 and ZnCl Q Also useful arethe corresponding monoquinoline complexes such as CoCl Q. Useful aminecomplexes include the mono-(ethylenediamine)-, bis- (ethylenediamine)-,tris(ethylenediamine)-, bis( 1,2- propanediamine)-, and bis-(l,3-propanediamine)- complexes of salts such as copper sulfate. Typicalpyridine complexes include NiCl (py and CuCl (py) where py is pyridine.

The foregoing metal salts and their complexes are used in ionic media,preferably in aqueous solutions. However, nonaqueous media can beemployed such as alcohols, for example, methyl alcohol, ethyl alcohol,butyl alcohol, heptyl alcohol, decyl alcohol, and the like. Mixtures ofalcohol and water can be used. Also useful are ionic mixtures of alcoholwith other miscible solvents of the types disclosed hereinbefore. Thesolution concentration is generally in the range from about 0.1 weightpercent metal salt or complex based on the total weight of the solutionup to a saturated solution, preferably from about one to about tenweight percent metal salt or complex. The pH of the metal salt orcomplex solution can range from about 4 to 14, but is generallymaintained in the basic range, i.e., greater than 7, are preferably fromabout 10 to about 13.

The step of contacting the phosphorus compound treated substrate withthe solution of metal salt is generally conducted at a temperature belowthe softening point of the substrate, and below the boiling point of thesolvent, if one is used. Generally the temperature is in the range ofabout 30 to 1 10 C., preferably from about 50 to C. The time of contactcan vary considerably, depending on the nature of the substrate, thecharacteristics of the metal salts employed and the contact temperature.However, the time of contact is generally in the range of about 1.0 to30 minutes, preferably about 5 to 10 minutes.

Depending on the conditions employed in the two treatment steps, theduration'of the treatments, and the nature of the substrate treated, theresulting treated surface may be either (1) conductive, such that thesurface can be readily electroplated by conventional techniques, or (2)nonconductive. In the latter instance the treated surface containsactive or catalytic sites that render the surface susceptible to furthertreatment by electroless plating processes that produce a conductivecoating on the plastic surface. Such a conductive coating is thencapable of being plated by conventional electrolytic processes.

The treated substrates that results from contacting the phosphoruscompound treated surface with a metal salt solution can be subjected toa process that has become known in the art as electroless plating orchemical plating. In a typical electroless plating process, a catalyticsurface is contacted with a solution of a metal salt under conditions inwhich the metallic ion of the metal salt is reduced to the metallicstate and deposited on the catalytic surface. A suitable chemicaltreating bath for the deposition of a nickel coating on the catalyticsurface produced in accordance with the process of the invention cancomprise, for example, a solution of a nickel salt in an aqueoushypophosphite solution. Suitable hypophosphites include the alkali metalhypophosphites such as sodium hypophosphite and potassium hypophosphite,and the alkaline earth metal hypophosphites such as calciumhypophosphite and barium hypophosphite. Other suitable metal salts foruse in the chemical treating bath include the metal salts describedhereinbefore with respect to the metal salt treatment of thephosphorus-treated substrate of the invention. Other reducing mediainclude formaldehyde, hydroquinone and hydrazine. Other agents, such asbuffering agents, complexing agents, and other additives are included inthe chemical plating solutions or baths. Suitable metals, solutions andconditions for electroplating are described in Metal Finishing GuidebookDirectory for 1967, published by Metals and Plastics Publications, Inc.,Westwood, NJ.

In one embodiment of the invention, wherein electroless metal plating isemployed, the metal salt or complex is provided by the electroless metalplating bath, so that the treatment of the phosphorus compound treatedsubstrate with the solution of metal salt or complex thereof can beeliminated as a separate step. Herein, the substrate is subjected to thelow oxidation state phosphorus compound and thereafter subjected toelectroless metal plating as described hereinbefore.

The treated substrates of the invention can be electroplated by theprocesses known in the art. The article is generally used as thecathode. The metal desired to be plated is generally dissolved in anaqueous plating bath, although other media can be employed. Generally, asoluble metal anode of the metal to be plated can be employed. ln someinstances, however, a carbon anode or other inert anode is used.

The following examples serve to illustrate the invention but are notintended to limit it. Unless specified otherwise, all temperatures arein degrees centigrade and parts are understood to be expressed in partsby weight.

EXAMPLE 1 A half mole of NaOC H was prepared by adding 11.5 grams ofsodium to 300 ml. of ethanol. A low oxidation state phosphorus compoundwas prepared by stirring at room temperature for several hours a mixtureof 0.5 mole of white phosphorus with the NaOC H solution. Samples ofpolyurethane, a graft copolymer of polybutadiene, styrene andacrylonitrile (ABS), and polyvinylchloride were immersed in thissolution for about 3 minutes at room temperature, exposed to air for 5minutes, washed with water and immersed in an electroless bath preparedfrom 40 ml. ofwater, ml. of 28 percent NH OH, 1.8 grams of NiCl 6H O and1 gram of NaH PO After 2 minutes in the bath, the plastics had obtainedadherent, conductive coatings. The conductivity of each sample was inthe range ofO to 20 ohms per 0.75 cm.

EXAMPLE 2 A low oxidation state phosphorus compound was prepared fromwhite phosphorus, ethanol and sodium ethoxide as described in Example 1.A sample of polyurethane was subjected to the compound for 30 seconds atroom temperature, washed with water for 30 seconds and immersed in a 5percent ammoniacal solution of nickel chloride at room temperature for[0 minutes. An adherent nickel-phosphorus coating was formed. The samplewas washed with water for 30 seconds and then subjected to anelectroless bath containing 100 ml. of NH OH, 1.0 gram of NaH PO and 50ml. of a solution prepared by dissolving grams of NiCl -6H O in 300 ml.of water. After 95 seconds, the polyurethane was removed and was foundto have an adherent, conductive coating.

EXAMPLE 3 A low oxidation state phosphorus compound solution wasprepared from 1 mole NaOC H 1 mole yellow phosphorus and 600 ml. ofethanol. An ABS sample was subjected to the solution at room temperaturefor 2 minutes and then dried in air for 1 minute. The sample wassubjected to a solution containing 5 grams of AgNO 100 ml. of water and100 ml. of concentrated NhqOH for about 5 minutes. The resulting samplehad a silver-phosphorus coating at the surface of the substrate. Thetreated sample was subjected to the electroless bath of Example 2 at 70C. to form a conductive coating.

EXAMPLES 4l3 Samples ofABS were subjected to a solution ofalow-oxidation state phosphorus compound at room temperature for about 3minutes, air dried and subjected to electroless metal plating asdescribed in Example 2 to provide adherent, conductive coatings on thesubstrates. The low oxidation state phosphorus compound solution wasprepared for dissolving the following nucleophilic reagents ororganometallic compounds in the following solvents and then adding whitephosphorus to the solution in a 1 to 1 mole ratio with the reagent orcompound:

Example Reagent or Compound Solvent 4 Sodium propoxide Propyl alcohol 5Sodium butoxide Butanol 6 Sodium hydroxide Methanol 7 Sodium hydroxideEthanol 8 Sodium ethoxide Ethanol 9 Sodium methoxide Methanol l0Butylmagnesiurn bromide Eth \l ether ll Sodium amide Ethanol 12Sodium-scc-butyl mercaptide Ethanol l3 Triethyl aluminum TetrahydrofuranEXAMPLES 14-26 In these examples, various solvents were employed. Unlessotherwise indicated, the substrate was subjected to the low oxidationstate phosphorus compounds at room temperature for l to 3 minutes,dried, rinsed with water, and subjected to electroless metal plating asdescribed in Example 2. In each instance, a conductive surface wasobtained. Also unless indicated otherwise, the nucleophilic reagent ororganometallic compound was added to white phosphorus in the solvent.

EXAMPLES 27-30 Samples of ABS were subjected to a solution for 10minutes at room temperature prepared by mixing yellow phosphorus,ethanol and sodium ethoxide. The samples were then dried in air for 1minute, rinsed with water and wiped dry. The plastic strips werethereafter immersed in the following 1 liter electroless baths for 15minutes (20 minutes in Example 30) to obtain an adherent, conductivecoating:

Example Electroless Bath 27 Acid Nickel Bath Nickel chloride 30 g.Sodium glycollate 50 g Sodium hypophosphite 10 pH 4-6 Temperature 190 F.

28 Basic Nickel Bath Nickel chloride 30 g. Sodium citrate g Ammoniumchloride 50 g Sodium hypophosphite 10 g. Temperature C.

29 Cobalt Bath Cobalt chloride 30 g Sodium citrate 35 g. NH Cl 50 g.NaH,PO, 20 g. pH 9-10 Temperature 90-95 C.

30 Copper Bath Copper nitrate 15 g.

NaHCO l g. Sodium citrate 30 g. NaOH 30 g. formaldehyde (38%) 100 ml. pH1 L Room temperature EXAMPLE 31 minutes in the solution, at roomtemperature, the plastic was air dried for 1 minute, dried in an aircirculating oven at 85 C. for 20 minutes, air dried for 1 minute, rinsedwith water and wiped dry. The treated specimen was then electrolessplated as described in Example 2.

EXAMPLE 32 An ABS disk was subjected for minutes to the low oxidationstate phosphorus compound solution of Example 8 at room temperature, airdried for 2 minutes and electroless plated with nickel in a MacDermidElectroless Nickel No. 28 Solution (acid) for 3 minutes. Thereafter, thedisk was elec troplated with copper in a Udylite bright acid copperplating bath at a current density of40 amperes per cubic foot. Theadhesion of the plated metal to the plastic surface (peel strength),measured by the quantity of force required to pull an inch wide strip ofmetal away from the plastic surface, was 10.8 pounds per inch.

EXAMPLE 32 Additional methanol was added to the low oxidation statephosphorus compound solution of Example 9. Five days later, an ABS diskwas immersed in this solution for 5 minutes at 50 C., air dried forseconds, oven dried (at 85 C.) for 2 minutes, air dried for 15 seconds,rinsed with water for 30 seconds and wiped with a paper towel. Theplastic was then electroless plated and electroplated as described inExample 32 except that the time the plastic was in the electroless bathwas 2 minutes. The peel strength was determined to be 17.0 pounds perinch.

EXAMPLES 33-39 The following substrates are plated with metals by theprocedure of Example 32:

Example Substrate Polyethylene Polystyrene PolymethylmethacrylateCardboard Paper Asbestos cement WoocL.

EXAMPLES 40-42 Example Substrate 40 Porcelain 4| Neoprene rubber 42Glass ill EXAMPLE 43 Several samples of ABS were immersed in a solutionof a low oxidation state phosphorus compound. The solution was preparedby adding 7 grams of lithium to 600 milliliters of absolute ethanol,adding 3] grams of yellow phosphorus thereto with stirring andthereafter mixing 20 milliliters of the resulting solution with 600milliliters of ethanol. The phosphorus constituted about 0.20 weightpercent based on the total weight of the solution. Immersion time was 3minutes and the temperature was 25 C. The samples were withdrawn intothe air for 3 minutes and then electroless nickel plated for 3 minutesat -88 C. Thereafter, the samples were electroplated as follows: about2.5 mils of nickel were applied by employing the treated ABS as thecathode, and using a nickel anode, in a Watts Nickel Bath. The resultingaverage adhesion was 18.0 pounds per inch.

EXAMPLE 44 Example 43 was repeated except that instead of immersing theABS samples in the low oxidation state phosphorus compound solution, thesolution was sprayed on the substrate by an airless spray gun whichemployed nitrogen. The resulting samples had adherently bound coatingson their surfaces.

This Example illustrates an additional method of subjecting a substrateto the low oxidation state phosphorus compound.

Various changes and modifications can be made in the process andproducts of this invention without departing from the spirit and scopeof the invention. For example, a substrate can be mechanically orchemically etched, if desired, prior to subjection to the low oxidationstate phosphorus compound. The various embodiments of the inventiondisclosed herein serve to further illustrate the invention but are notintended to limit it.

I claim:

1. A process which comprises coating a substrate by subjecting thesubstrate to at least one reaction product of elemental white phosphorusand a nucleophilic reagent or organometallic compound in a solvent.

2. The process of claim 1 wherein the substrate is a plastic.

3. A process wherein the treated substrate resulting from the process ofclaim 1 is subjected to electroless metal plating to deposit anelectroless conductive coating on the treated substrate.

4. A process wherein the substrate resulting from the process of claim 3is electroplated to deposit an adherent metal coating on the conductivecoating.

5. The process of claim 4 wherein the nucleophilic reagent is sodiumethoxide.

6. The process of claim 4 wherein the nucleophilic reagent is lithiumethoxide.

7. The process of claim 4 wherein the plastic is a graft copolymer ofpolybutadiene, styrene and acrylonitrile.

8. The process of claim 4 wherein the plastic is polyvinylchloride.

9. The process of claim 4 wherein the plastic is polypropylene.

10. A process which comprises subjecting a substrate to at least onereaction product of elemental white phosphorus and a nucleophilicreagent or organometallic compound in a solvent and thereaftersubjecting the treated substrate to a metal salt or complex thereofwherein the metal salt is selected from Groups 1B, 118, NE, VB, VlB,V118 and VIII of the Periodic Table.

11. The process of claim 10 wherein the nucleophilic reagent is analkali metal alkoxide.

12. A process wherein the treated substrate resulting from the processof claim 10 is subjected to electroless metal plating to depositaconductive coating on the treated substrate.

l3. A process wherein the substrate resulting from the process of claim12 is electroplated to deposit an adherent metal coating on theconductive coating.

14. A process wherein the treated substrate resulting from the processof claim is electroplated to deposit an adherent metal coating on thetreated substrate.

15. An article having a low oxidation state phosphorus compounddeposited at the surface ofa substrate, wherein said low oxidation statephosphorus compound is the reaction product of elemental phosphorus anda nucleophilic reagent or organometallic compound.

16. The article ofclaim wherein the substrate is a plastic.

17. The article of claim 16 wherein the nucleophilic reagent is sodiumethoxide.

18. The article of claim 16 wherein the nucleophilic reagent is lithiumethoxide.

19. The article of claim 16 wherein the plastic is a graft copolymer ofpolybutadiene, styrene and acrylonitrile.

20. The article of claim 16 wherein the plastic is polyvinyl chloride.

21. The article of claim 16 wherein the plastic is polypropylene.

22. An article having an adherent metal-phosphorus coating on thesurface of a substrate, wherein said metal-phosphorus coating is thereaction product of a metal salt or complex thereof and a low oxidationstate phosphorus compound, wherein said low oxidation state phosphoruscompound is the reaction product of elemental phosphorus and anucleophilic reagent or organometallic, compound, and wherein the metalof the metal salt or complex thereof is selected from Groups [8, 11B,IVB, VB, VlB, VlIB and VIII ofthe Periodic Table.

23. The article of claim 22 wherein the substrate is a plastic.

24. The article ofclaim 23 wherein the nucleophilic reagent is an alkalimetal alkoxide.

25. The article of claim 23 having an adherent metal coatingelectrolytically deposited on said metal-phosphorus coating.

26. The article of claim 23 having a conductive electroless metalcoating deposited on said metal-phosphorus coating.

27. The article ofclaim 26 having an adherent metal coatingelectrolytically deposited on the conductive coating.

28. The article of claim 27 wherein the plastic is a graft copolymerofpolybutadiene, styrene and acrylonitrile.

29. The article of claim 27 wherein the plastic is polyvinyl chloride.

30. The article of claim 15 having a conductive electroless metalcoating deposited on said low oxidation state phosphorus compound.

31. The article of claim 27 wherein the plastic is polypropylene.

32. The article of claim 30 having an adherent metal coatingelectrolytically deposited on the conductive coating.

33. The article of claim 32 wherein the substrate is a graft copolymerof polybutadiene, styrene and acrylonitrile.

34. The article of claim 32 wherein the substrate is polyvinyl chloride.

35. The article of claim 32 wherein the substrate is polypropylene.

36. The article of claim 22 wherein said nucleophilic reagent has theformula M2,, wherein M is an alkali metal or an alkaline earth metal, yis 1 or 2, and Z is hydroxide, alkoxide, amide, sulfite, thiosulfate,mercaptide, cyanate, thiocyanate, cyanide or azide.

37. The article of claim 36 wherein the nucleophilic reagent is sodiummethoxide.

38. The article of claim 36 wherein the nucleophilic reagent is sodiumethoxide.

39. The article of claim 36 wherein the nucleophilic reagent is lithiumethoxide.

40. The article of claim 22 wherein said organometallic compound has theformula R,D wherein R is alkyl of one to 18 carbon atoms, aryl of six to18 carbon atoms, alicyclic of five to 18 carbon atoms, aralkyl of six tol8 carbon atoms or alkylaryl of six to 18 carbon atoms, D is a metalselected from Groups 1A, II and "IA of the Periodic Table, and .t is lto 3.

41. The article of claim 40 wherein the organometallic compound istriethyl aluminum.

42. The process of claim 10 wherein said nucleophilic reagent has theformula MZ wherein M is an alkali metal or an alkaline earth metal, y isl or 2, and Z is hydroxide, alkoxide, amide, sulfite, thiosulfate,mercaptide, cyanate, thiocyanate, cyanide or azide.

43. The process of claim 42 wherein the nucleophilic reagent is sodiummethoxide.

44. The process of claim 42 wherein the nucleophilic reagent is sodiumethoxide.

45. The process of claim 42 wherein the nucleophilic reagent is lithiumethoxide.

46. The process of claim 42 wherein the nucleophilic reagent is sodiumamide.

47. The process of claim 42 wherein the nucleophilic reagent issodium-sec-butyl mercaptide.

48. The process of claim 10 wherein said organometallic compound has theformula R D wherein R is alkyl or one to 18 atoms, aryl of six to 18carbon atoms, alicyclic of five to l8 carbon atoms, aralkyl of six to 18carbon atoms or alkylaryl of six to 18 carbon atoms, D is a metalselected from Groups IA, ll and [HA ofthe Periodic Table, and x is l to3.

49. The process of claim 48 wherein the organometallic compound istriethyl aluminum.

50. The process of claim 48 wherein the organometallic compound isbutylmagnesium bromide.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION mmwo. 65 0 Datedrch 21; 1912 Invent-(8) V Kingso Chingtsung-Lin It is certified thaterror appears in the above-identified patent. and that said LettersPatent are hereby corrected as shown below:

Column 2, line 66, "wherein the" should read ----wherein the 1phosphorusm Column 6, line 26 "are preferrably" should read ---endpreferablyu Column 7, line 62, "Nb 0 Should read -1--J-*.;IH O line 73"for dissolving" should read ---by dissolving--. Column 8', line 36 ".(CH 21" should read @M.(C H -\1---. Column 9, line 3"NaOH 30 9" shouldread ms 20 -g-- Column 12, line 41 "alkyl or" should read Thiscertificate supersedes Certificate of Correction issued August 1, 1972.

Signed and. sealed this 19th day of March 197A.

' (SEAL) Attestz EDWARD M.FLETCHER,IJR. c; MARSHALL'DANN Attest ingOfficer Commissioner of Patents zg g UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. 3,650,803 Dated March 21, 1972 I vKingso Chingtsung Lin It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

I Column 6, line 26 "are preferrably" should read --and preferably----.Column 7, line 62, "Nh OH" .should read -.-I ,IH OH---; line 73 "fordissolving" should read --by dissol\zing--.. Column 8, line 36 "(C H a1"should read (C H Al--. Column 9, line 3"NaOH 30 9" should read --NaOH 20g-. Column 12, line 41 "alkyl or" should read ---a1kyl of-.

Signed and sealed this 1st day of August 1972-.

(SEAL) Attest':

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer I Commissionerof Patents

2. The process of claim 1 wherein the substrate is a plastic.
 3. Aprocess wherein the treated substrate resulting from the process ofclaim 1 is subjected to electroless metal plating to deposit anelectroless conductive coating on the treated substrate.
 4. A processwherein the substrate resulting from the process of claim 3 iselectroplated to deposit an adherent metal coating on the conductivecoating.
 5. The process of claim 4 wherein the nucleophilic reagent issodium ethoxide.
 6. The process of claim 4 wherein the nucleophilicreagent is lithium ethoxide.
 7. The process of claim 4 wherein theplastic is a graft copolymer of polybutadiene, styrene andacrylonitrile.
 8. The process of claim 4 wherein the plastic ispolyvinylchloride.
 9. The process of claim 4 wherein the plastic ispolypropylene.
 10. A process which comprises subjecting a substrate toat least one reaction product of elemental white phosphorus and anucleophilic reagent or organometallic compound in a solvent andthereafter subjecting the treated substrate to a metal salt or complexthereof wherein the metal salt is selected from Groups IB, IIB, IVB, VB,VIB, VIIB and VIII of the Periodic Table.
 11. The process of claim 10wherein the nucleophilic reagent is an alkali metal alkoxide.
 12. Aprocess wherein the treated substrate resulting from the process ofclaim 10 is subjected to electroless metal plating to deposit aconductive coating on the treated substrate.
 13. A process wherein thesubstrate resulting from the process of claim 12 is electroplated todeposit an adherent metal coating on the conductive coating.
 14. Aprocess wherein the treated substrate resulting from the process ofclaim 10 is electroplated to deposit an adherent metal coating on thetreated substrate.
 15. An article having a low oxidation statephosphorus compound deposited at the surface of a substrate, whereinsaid low oxidation state phosphorus compound is the reaction product ofelemental phosphorus and a nucleophilic reagent or organometalliccompound.
 16. The article of claim 15 wherein the substrate is aplastic.
 17. The article of claim 16 wherein the nucleophilic reagent issodium ethoxide.
 18. The article of claim 16 wherein the nucleophilicreagent is lithium ethoxide.
 19. The article of claim 16 wherein theplastic is a graft copolymer of polybutadiene, styrene andacrylonitrile.
 20. The article of claim 16 wherein the plastic ispolyvinyl chloride.
 21. The article of claim 16 wherein the plastic ispolypropylene.
 22. An article having an adherent metal-phosphoruscoating on the surface of a substrate, wherein said metal-phosphoruscoating is the reaction product of a metal salt or complex thereof and alow oxidation state phosphorus compound, wherein said low oxidationstate phosphorus compound is the reaction product of elementalphosphorus and a nucleophilic reagent or organometallic, compound, andwherein the metal of the metal salt or complex thereof is selected fromGroups IB, IIB, IVB, VB, VIB, VIIB and VIII of the Periodic Table. 23.The article of claim 22 wherein the substrate is a plastic.
 24. Thearticle of claim 23 wherein the nucleophilic reagent is an alkali metalalkoxide.
 25. The article of claim 23 having an adherent metal coatingelectrolytically deposited on said metal-phosphorus coating.
 26. Thearticle of claim 23 having a conductive electroless metal coatingdeposited on said metal-phosphorus coating.
 27. The article of claim 26having an adherent metal coating electrolytically deposited on theconductive coating.
 28. The article of claim 27 wherein the plastic is agraft copolymer of polybutadiene, styrene and acrylonitrile.
 29. Thearticle of claim 27 wherein the plastic is polyvinyl chloride.
 30. Thearticle of claim 15 having a conductive electroless metal coatingdeposited on said low oxidation state phosphorus compound.
 31. Thearticle of claim 27 wherein the plastic is polypropylene.
 32. Thearticle of claim 30 having an adherent metal coating electrolyticallydeposited on the conductive coating.
 33. The article of claim 32 whereinthe substrate is a graft copolymer of polybutadiene, styrene andacrylonitrile.
 34. The article of claim 32 wherein the substrate ispolyvinyl chloride.
 35. The article of claim 32 wherein the substrate ispolypropylene.
 36. The article of claim 22 wherein said nucleophilicreagent has the formula MZy wherein M is an alkali metal or an alkalineearth metal, y is 1 or 2, and Z is hydroxide, alkoxide, amide, sulfite,thiosulfate, mercaptide, cyanate, thiocyanate, cyanide or azide.
 37. Thearticle of claim 36 wherein the nucleophilic reagent is sodiummethoxide.
 38. The article of claim 36 wherein the nucleophilic reagentis sodium ethoxide.
 39. The article of claim 36 wherein the nucleophilicreagent is lithium ethoxide.
 40. The article of claim 22 wherein saidorganometallic compound has the formula RxD wherein R is alkyl of one to18 carbon atoms, aryl of six to 18 carbon atoms, alicyclic of five to 18carbon atoms, aralkyl of six to 18 carbon atoms or alkylaryl of six to18 carbon atoms, D is a metal selected from Groups IA, II and IIIA ofthe Periodic Table, and x is 1 to
 3. 41. The article of claim 40 whereinthe organometallic compound is triethyl aluminum.
 42. The process ofclaim 10 wherein said nucleophilic reagent has the formula MZy wherein Mis an alkali metal or an alkaline earth metal, y is 1 or 2, and Z ishydroxide, alkoxide, amide, sulfite, thiosulfate, mercaptide, cyanate,thiocyanate, cyanide or azide.
 43. The process of claim 42 wherein thenucleophilic reagent is sodium methoxide.
 44. The process of claim 42wherein the nucleophilic reagent is sodium ethoxide.
 45. The process ofclaim 42 wherein the nucleophilic reagent is lithium ethoxide.
 46. Theprocess of claim 42 wherein the nucleophilic reagent is sodium amide.47. The process of claim 42 wherein the nucleophilic reagent issodium-sec-butyl mercaptide.
 48. The process of claim 10 wherein saidorganometallic compound has the formula RxD wherein R is alkyl or one to18 atoms, aryl of six to 18 carbon atoms, alicyclic of five to 18 carbonatoms, aralkyl of six to 18 carbon atoms or alkylaryl of six to 18carbon atoms, D is a metal selected from Groups IA, II and IIIA of thePeriodic Table, and x is 1 to
 3. 49. The process of claim 48 wherein theorganometallic compound is triethyl aluminum.
 50. The process of claim48 wherein the organometallic compound is butylmagnesium bromide.